A garage door is a large door on a garage that opens either manually or by an electric motor. Garage doors are frequently large enough to accommodate automobiles and other vehicles. Small garage doors may be made in a single panel that tilts up and back across the garage ceiling. Larger doors are usually made in several jointed panels that roll up on tracks across the garage ceiling, or into a roll above the doorway. The operating mechanism is spring-loaded or counterbalanced to offset the weight of the door and reduce human or motor effort required to operate the door.
A torsion spring counterbalance system consists of one or two tightly wound up springs on a steel shaft with cable drums at both ends. The entire apparatus mounts on the header wall above the garage door and has three supports: a center bearing plate with a steel or nylon bearing and two end bearing plates at both ends. The springs themselves consist of the steel wire with a stationary cone at one end and a winding cone at the other end. The stationary cone is attached to the center bearing plate. The winding cone consists of holes every 90 degrees for winding the springs and set screws to secure the springs to the shaft. Steel counterbalance cables run from the roller brackets at the bottom corners of the door to a notch in the cable drums. When the door is raised, the springs unwind and the stored tension lifts the door by turning the shaft, thus turning the cable drums, wrapping the cables around the grooves on the cable drums. When the door is lowered, the cables unwrap from the drums and the springs are rewound to full tension.
Garage doors may cause injury and property damage (including expensive damage to the door itself) in several ways. A common cause of injury is from falling garage doors. A garage door with a broken torsion spring, or the wrong strength torsion spring, can fall. Because the effective mass of the door increases as the garage door sections transfer from horizontal to vertical door tracks, a falling garage door accelerates rapidly.
What is needed then is a simple safety device that can stop or inhibit progress of a free-falling garage door.
In one aspect, embodiments disclosed herein relate to a garage door assembly including a torsion spring counterbalance apparatus mounted on a header wall above a garage door, the apparatus including at least one spring wound on a shaft, and a safety device, the safety device including a capture device mounted on the header wall above the garage door, and a catch device attached to the shaft at a location proximate to the capture device on the header wall. The catch device rotates with the torsion spring counterbalance shaft, and the catch device is capable of extending away from the shaft under centrifugal force to engage the capture device and thereby stop the garage door from further free-falling.
In another aspect, embodiments disclosed herein relate to a garage door assembly including a torsion spring counterbalance apparatus mounted on a header wall above a garage door, the apparatus including at least one spring wound on a shaft, and a safety device, the safety device including a hook mounted on the header wall above the garage door, and a chain attached at two locations along a length of the counterbalance shaft proximate to the hook, wherein a length of the chain between the two attachment locations is greater than the shaft length between the two attachment locations. When the shaft is rotating without resistance from the torsion spring counterbalance apparatus, the chain is configured to extend away from the shaft under centrifugal force and engage the hook to stop the garage door from free-falling.
In yet another aspect, embodiments disclosed herein relate to a method of stopping a free-falling garage door, the garage door including a torsion spring counterbalance apparatus mounted on a header wall above the garage door and having at least one spring wound on a shaft, the method including providing a catch device attached to the shaft and that rotates with the shaft, and further providing a capture device attached to the header wall and proximate to the catch device, and configuring the catch device and corresponding capture device, such that when lowering the garage door and rotating the shaft at a lower speed due to increasing resistance provided by the torsion spring counterbalance apparatus, the catch device does not engage the capture device. The catch device and corresponding catch device are also configured such that when lowering the garage door and rotating the shaft at a higher speed due to little or no resistance provided by the torsion spring counterbalance apparatus, the catch device extends away from the shaft due to centrifugal force and engages the capture device, and thereby stops further lowering the garage door.